city, everybody pitching in as parts of national day of service. >> we're really looking forward to coming to the and fine finding a way to contribute. >> reporter: the complex will provide affordable housing for bay area families, but those chosen families do have to put in some work. >> our model is base on a hand up, not a handout. so our homers volunteer and they are helping to boil the home that they will live in. >> reporter: it's actually the largest habitat for humanity project in the world. rob alvarado, who was working on the roof today was here when construction first started and came back for this national day of service. >> i just feel like, if in your life, you had a lot of opportunities, and you have had success and you just feel fortunate, you should crotout and help other people that need that same opportunity. >> reporter: as you can see a lot of these units still have a long way to go, but today is parts of a last-minute push to get this project completed. habitat for humanity is hoping to have all the families moved into the condo units by april. in tally ciscoe